Multi-pulley and force problem

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In summary, the tension of the ropes in this system is equal throughout, due to the constraints of the pulleys. T1 is equal to the weight of the block, T2 and T3 are equal to half the weight of the block, and T4 must equal the weight plus any additional force to keep the system stable. T5 cannot equal the weight, as this would cause an imbalance of forces and acceleration.
  • #1
narfarnst
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Homework Statement


http://i829.photobucket.com/albums/zz220/narfarnst/problem.jpg

Find T1 through T5 and the force on the right side of the diagram above.
(The force balances the weight, so the system is stationary).
EDIT: Oh, and the pulleys and ropes are massless and there is no friction.

Homework Equations


F=ma, various rearrangements of T=m(g+/-a)

The Attempt at a Solution


Based on mostly intuition I've concluded that T1=mg (very sure about that one).
I also think that T2 and T3 equally share the weight, so T2=T3=1/2mg.
T4 has to equal mg+F for it to keep the system up
And I'm not sure about T5 but I'm thinking that it equals mg because the system isn't accelerating.
But I'm not at all 100% sure an these.

Thanks!
 
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  • #2
The single rope has three segments. Each segments must have the same tension. That is the basic constrain in the pulleys.
 
  • #3
narfarnst said:
Based on mostly intuition I've concluded that T1=mg (very sure about that one).
Intuition is fine, if you can then find a reason why it is so. Gravity and
the tension of the rope are the only forces on the block, so they
must be equal and opposite.

I also think that T2 and T3 equally share the weight, so T2=T3=1/2mg.
Because the pulleys have no friction and no mass, there must be the
same tension in the ropes on both sides. (if there were not they would
start to accelerate infinitely fast)
T4 has to equal mg+F for it to keep the system up
Ok
And I'm not sure about T5 but I'm thinking that it equals mg because the system isn't accelerating.
but then the forces on the top pulley would be unbalanced
 

1. What is a multi-pulley system?

A multi-pulley system is a mechanical device that consists of multiple pulleys and ropes or belts. It is used to change the direction of a force, making it easier to lift or move heavy objects by distributing the force over multiple ropes or belts.

2. How does a multi-pulley system work?

A multi-pulley system works by using the principle of mechanical advantage. The more pulleys in the system, the greater the mechanical advantage, meaning less force is required to lift or move an object. As the force is distributed over multiple ropes or belts, the individual tensions are reduced, making it easier to lift or move the object.

3. What factors affect the force required in a multi-pulley system?

The force required in a multi-pulley system is affected by the number of pulleys, the weight of the object being lifted, and the friction between the ropes or belts and the pulleys. The more pulleys in the system, the less force is required. A heavier object will require more force, and higher friction will also increase the force needed.

4. How do you calculate the mechanical advantage of a multi-pulley system?

The mechanical advantage of a multi-pulley system can be calculated by dividing the output force (the force required to lift or move the object) by the input force (the force applied to the rope or belt). For example, if an object with a weight of 100N requires an input force of 20N to lift it using a multi-pulley system, the mechanical advantage would be 100N/20N = 5.

5. What are some real-life applications of multi-pulley systems?

Multi-pulley systems are commonly used in cranes, elevators, and other heavy machinery to lift and move heavy objects. They are also used in rock climbing equipment, sailboats, and zip lines to reduce the amount of force required for certain activities. In addition, multi-pulley systems can be found in exercise equipment and weightlifting machines to provide resistance and make it easier to lift weights.

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